This is an application for the purchase of a new transmission electron microscope (TEM) at the University of Wisconsin-Madison. A decade ago, there were at least six transmission electron microscopes available for the general use of biology programs on this campus, but that number has dwindled to three as older instruments have been deactivated (or in one case moved with a departing faculty member). The remaining electron microscopes are heavily used, and the research interests of several new faculty hires have forced us to address the dwindling TEM resources on campus. The requested instrument will replace one of the remaining instruments, a Phillips EM 300 that was originally purchased in 1967. As elaborated upon later, this 35 year old instrument will soon reach a point where continued repair will be impossible. The Phillips EM has served primarily the needs of research programs working on aspects of DNA metabolism, and has been maintained and operated by Ross Inman. The new TEM will see an expanded role on campus, serving both traditional users and a wider variety of research programs. It will be set up by Ross Inman, John White, and Michael Cox. It will be maintained by technicians trained by Ross Inman and John White. In addition, its operation will be integrated with that of the two other electron microscopes on campus (of more recent vintage), which are located in the veterinary and medical schools.